A number of processes exist in which a polymeric film or sheet material is formed on or against a release sheet, and then separated from the release sheet after cooling or curing. Curing the polymeric film or sheet material (when necessary) can be accomplished by heat, by peroxide catalyst, or by radiation (e.g., ultraviolet radiation or electron beam radiation). The release sheet provides a surface from which the set polymeric film or sheet material can be separated, and also imparts a desired surface finish to the set polymeric film or sheet material. For example, a desired textured surface can be provided on the polymeric film or sheet material by forming the polymeric film or sheet material on or against a release sheet having a textured surface that is a mirror image of the desired textured surface. One example of making a set polymeric film or sheet material includes providing a release sheet having a desired surface effect, such as high gloss or texturing, and then casting a reactive urethane resin onto the provided release sheet. Typically, the reactive urethane resin is formed by mixing one or more diisocyanates and one or more polyol components, along with any other additives such as crosslinkers and accelerators (if desired). Upon mixing, the components begin to react. After mixing, the reactive urethane resin is applied to the release sheet where it sets, forming the set polymeric film or sheet material.
Release sheets can be made by applying a coating of an electron beam radiation curable material to one surface of a web substrate; pressing the coated side of the substrate against a replicative surface having a desired surface effect; irradiating the coating with electron beam radiation to cure the coating; and stripping the substrate from the replicative surface with the cured coating adhered to the substrate. The replicative surface can be a metal roll with a pattern engraved in its surface if a textured release sheet surface is desired, or a highly polished surface having a low surface roughness, if a high gloss release sheet surface is desired.